Tail
Recursion (review)
fac(n)
= f1(1, n, 1);
fac(n) = n <= 1 ? 1 : n*fac(n-1);f1(a, n, x) = x <= n ? f1(a*x, n, x+1)
: a;
f1(a*x, n, x+1) : a;Òtail-recursiveÓ
non-tail-recursive
Functions produced by McCarthyÕs transformation are all Òtail-recursiveÓ, meaning that the result of the function can be wholly delegated to some other defined function call.